RE: [PATCH 3/3] libc: Replace one letter member names in __tzrule_struct

[Torbjorn SVENSSON <torbjorn.svensson@st.com>]

Hello!

Thanks for the feedback Jeff.

Regarding the alternative to using "__" prefix for the members; would it be better to move line 105-123 from newlib/libc/include/time.h to newlib/libc/time/local.h, thus not exposing it in the API?
The lines in question are:
typedef struct __tzrule_struct
{
  char ch;
  int m;
  int n;
  int d;
  int s;
  time_t change;
  long offset; /* Match type of _timezone. */
} __tzrule_type;

typedef struct __tzinfo_struct
{
  int __tznorth;
  int __tzyear;
  __tzrule_type __tzrule[2];
} __tzinfo_type;

__tzinfo_type *__gettzinfo (void);



Would this change be easier to get accepted? If this approach is better, I guess the single letter member names can be kept too…
While I took another look at the change, I also noticed that the struct definition (not usage) is also present in these files:
newlib/libc/sys/linux/include/time.h
newlib/libc/sys/phoenix/include/time.h

I’m not sure in what situations those files are used and when the time.h file that I modified is used, but I guess they should be in sync regardless.

Thanks
Torbjörn

From: Jeff Johnston <jjohnstn@redhat.com> 
Sent: den 2 oktober 2020 01:21
To: Torbjorn SVENSSON <torbjorn.svensson@st.com>
Cc: Newlib <newlib@sourceware.org>
Subject: Re: [PATCH 3/3] libc: Replace one letter member names in __tzrule_struct

Hello, while I fully agree there is an issue (the struct was due to my initial check-in in 2005 based on glibc), the change will break API and thus technically requires a major release bump of newlib.  I would prefer to wait for something else
to require a major bump before making such a change.  In such a case, I also believe that the patch should either use double-underscores for the field names (e.g. __month) or hide the struct from regular users of time.h.

-- Jeff J.

On Thu, Oct 1, 2020 at 10:19 AM Torbjörn SVENSSON via Newlib <mailto:newlib@sourceware.org> wrote:
As discussed in GCC bug 97088
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97088), parameters in
prototypes of library functions should use reserved names, or no name
at all.

This patch replaces 'm', 'n', 'd' and 's' members in
'struct __tzrule_struct' to avoid possible clashes with user code in
case someone uses before including Newlib's time.h (or uses some
other conflicting definition)

Signed-off-by: Torbjörn SVENSSON <mailto:torbjorn.svensson@st.com>
---
 newlib/libc/include/time.h       |  8 ++++----
 newlib/libc/time/tzcalc_limits.c | 14 +++++++-------
 newlib/libc/time/tzset_r.c       | 22 +++++++++++-----------
 3 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/newlib/libc/include/time.h b/newlib/libc/include/time.h
index 3031590b4..6a540537f 100644
--- a/newlib/libc/include/time.h
+++ b/newlib/libc/include/time.h
@@ -105,10 +105,10 @@ void      _tzset_r        (struct _reent *);
 typedef struct __tzrule_struct
 {
   char ch;
-  int m;
-  int n;
-  int d;
-  int s;
+  int month; /* Month of year if ch=M */
+  int week; /* Week of month if ch=M */
+  int day; /* Day of week if ch=M, day of year if ch=J or ch=D */
+  int secs; /* Time of day in seconds */
   time_t change;
   long offset; /* Match type of _timezone. */
 } __tzrule_type;
diff --git a/newlib/libc/time/tzcalc_limits.c b/newlib/libc/time/tzcalc_limits.c
index e0ea6549c..b2163ed3d 100644
--- a/newlib/libc/time/tzcalc_limits.c
+++ b/newlib/libc/time/tzcalc_limits.c
@@ -34,13 +34,13 @@ __tzcalc_limits (int year)
       if (tz->__tzrule[i].ch == 'J')
        {
          /* The Julian day n (1 <= n <= 365). */
-         days = year_days + tz->__tzrule[i].d +
-           (isleap(year) && tz->__tzrule[i].d >= 60);
+         days = year_days + tz->__tzrule[i].day +
+           (isleap(year) && tz->__tzrule[i].day >= 60);
          /* Convert to yday */
          --days;
        }
       else if (tz->__tzrule[i].ch == 'D')
-       days = year_days + tz->__tzrule[i].d;
+       days = year_days + tz->__tzrule[i].day;
       else
        {
          const int yleap = isleap(year);
@@ -49,15 +49,15 @@ __tzcalc_limits (int year)

          days = year_days;

-         for (j = 1; j < tz->__tzrule[i].m; ++j)
+         for (j = 1; j < tz->__tzrule[i].month; ++j)
            days += ip[j-1];

          m_wday = (EPOCH_WDAY + days) % DAYSPERWEEK;

-         wday_diff = tz->__tzrule[i].d - m_wday;
+         wday_diff = tz->__tzrule[i].day - m_wday;
          if (wday_diff < 0)
            wday_diff += DAYSPERWEEK;
-         m_day = (tz->__tzrule[i].n - 1) * DAYSPERWEEK + wday_diff;
+         m_day = (tz->__tzrule[i].week - 1) * DAYSPERWEEK + wday_diff;

          while (m_day >= ip[j-1])
            m_day -= DAYSPERWEEK;
@@ -67,7 +67,7 @@ __tzcalc_limits (int year)

       /* store the change-over time in GMT form by adding offset */
       tz->__tzrule[i].change = days * SECSPERDAY +
-      tz->__tzrule[i].s + tz->__tzrule[i].offset;
+      tz->__tzrule[i].secs + tz->__tzrule[i].offset;
     }

   tz->__tznorth = (tz->__tzrule[0].change < tz->__tzrule[1].change);
diff --git a/newlib/libc/time/tzset_r.c b/newlib/libc/time/tzset_r.c
index 9e0cf834b..7117b51e6 100644
--- a/newlib/libc/time/tzset_r.c
+++ b/newlib/libc/time/tzset_r.c
@@ -115,9 +115,9 @@ _tzset_unlocked_r (struct _reent *reent_ptr)
            return;

          tz->__tzrule[i].ch = 'M';
-         tz->__tzrule[i].m = m;
-         tz->__tzrule[i].n = w;
-         tz->__tzrule[i].d = d;
+         tz->__tzrule[i].month = m;
+         tz->__tzrule[i].week = w;
+         tz->__tzrule[i].day = d;

          tzenv += n;
        }
@@ -142,22 +142,22 @@ _tzset_unlocked_r (struct _reent *reent_ptr)
              if (i == 0)
                {
                  tz->__tzrule[0].ch = 'M';
-                 tz->__tzrule[0].m = 3;
-                 tz->__tzrule[0].n = 2;
-                 tz->__tzrule[0].d = 0;
+                 tz->__tzrule[0].month = 3;
+                 tz->__tzrule[0].week = 2;
+                 tz->__tzrule[0].day = 0;
                }
              else
                {
                  tz->__tzrule[1].ch = 'M';
-                 tz->__tzrule[1].m = 11;
-                 tz->__tzrule[1].n = 1;
-                 tz->__tzrule[1].d = 0;
+                 tz->__tzrule[1].month = 11;
+                 tz->__tzrule[1].week = 1;
+                 tz->__tzrule[1].day = 0;
                }
            }
          else
            {
              tz->__tzrule[i].ch = ch;
-             tz->__tzrule[i].d = d;
+             tz->__tzrule[i].day = d;
            }

          tzenv = end;
@@ -172,7 +172,7 @@ _tzset_unlocked_r (struct _reent *reent_ptr)
       if (*tzenv == '/')
        sscanf (tzenv, "/%hu%n:%hu%n:%hu%n", &hh, &n, &mm, &n, &ss, &n);

-      tz->__tzrule[i].s = ss + SECSPERMIN * mm + SECSPERHOUR  * hh;
+      tz->__tzrule[i].secs = ss + SECSPERMIN * mm + SECSPERHOUR  * hh;

       tzenv += n;
     }
-- 
2.18.0